AU2006258281B2

AU2006258281B2 - A pump

Info

Publication number: AU2006258281B2
Application number: AU2006258281A
Authority: AU
Inventors: Patrik Andersson
Original assignee: Xylem IP Holdings LLC
Current assignee: Xylem IP Holdings LLC
Priority date: 2005-06-17
Filing date: 2006-06-05
Publication date: 2011-12-01
Anticipated expiration: 2026-06-05
Also published as: CN101198793A; SI1891331T1; EP1891331A1; RS51594B; DK1891331T3; ES2359333T3; SE527818C2; EP1891331B1; US8109730B2; MY147539A; PT1891331E; WO2006135304A1; DE602006019583D1; SE0501382L; PL1891331T3; CA2610567A1; CN101198793B; ATE495366T1; AU2006258281A1; HK1118090A1

Abstract

The invention relates to a pump for pumping contaminated liquid including solid matter, comprising a pump housing provided with a rotatable impeller (3) having at least one vane (9) and an impeller seat (4), the impeller seat (4) presenting at least one recess (13) in the top surface (11) thereof, a sheering/cutting action arising between an cutting edge (15) of said recess (13) and a lower edge (14) of the vane (9) as the impeller (3) rotates relative to the impeller seat (4) . Furthermore, the pump also comprises means for guiding the solid matter towards said recess (13) , the guiding means comprising at least one guide pin and at least one projection (20) , an upper surface (19) of the guide pin extending from a position contiguous to the most inner part of the vane (9) of the impeller (3) towards the impeller seat (4), and the projection (20) protruding from the impeller seat (4) .

Description

WO 2006/135304 PCT/SE2006/000663 1 A PUMP Technical field of the invention The present invention relates generally to the 5 field of pumps for sewage or waste water, and more specifically to a pump for pumping unscreened contaminated liquid including solid matter, such as plastic materials, hygiene articles, textile, rags, etc. The present invention also relates to pumps, the purpose of which is to provide a 10 uniform sludge from out of a raw material, such as slaughterhouse waste from a fish farming. More precisely, not necessarily counteract clogging of the pump, but instead cutting up the solid matter/raw material into pieces more adapted for subsequent manufacturing steps. Said pump 15 comprises a pump housing provided with a rotatable impeller having at least one vane, and an impeller seat, the impeller seat presenting at least one recess in the top surface thereof, a sheering/cutting action arising between an cutting edge of said recess and a lower edge of the vane as the 20 impeller rotates relative to the impeller seat. Background of the Invention In sewage stations, septic tanks, wells, etc., it often occurs that solid matter or pollutants, such as socks, 25 sanitary pads, paper, etc., clogs the submergible pump that is lowered into the basin of the system. The contaminations stick to the vanes of the impeller and become wound around the impeller. In order to get rid of the clogging matter, it is 30 known to equip centrifugal pumps with means for cutting up the solid matter. More precisely, the solid matter is cut up in smaller pieces between the vane of the impeller and a recess in the impeller seat of the pump housing, as is seen in for example DE 198,34,815 or US 5,516,261. In each of the 35 two referred documents it is just briefly shown how merely the edge between the leading edge of the vane and the tip of the surface of the vane of the impeller interacts with said recess. It is shown how said edge of the vane meets the WO 2006/135304 PCT/SE2006/000663 2 cutting edge of the recess in a direction parallel to the direction of rotation of the impeller. More precisely, both cutting edges are perpendicular to the direction of rotation of the impeller. In these cases a superfluously high force, 5 and thereby also a lot of energy, is needed to cut up the solid matter into smaller pieces. If the solid matter is not cut up sufficiently efficiently into discrete pieces, but the pieces has long uncut fibers still connecting them to each other, the solid 10 matter might clog the pump in an even more severe way. If the solid matter is semi-cut, as described, some pieces will get caught between the impeller and the pump housing and some pieces will still be to large to pass from the basin side of the impeller past the impeller. Thus, this will make the 15 rotation of the impeller heavy and the energy consumption will increase. In a worst case scenario, the impeller will get totally jammed and thus the pump may get seriously damaged. Such an unintentional shutdown is costly, due to expensive and cumbersome and unplanned maintenance work. 20 DE 1,528,694 shows a pump comprising an impeller seat presenting a number of recesses of different shape and orientation, which in conjunction with the impeller improves the cutting action. Nevertheless, solid matter having long fibers is still a problem as the fibers may get tangled among 25 the vanes of the impeller, resulting in a gradual decrease of the efficiency of the pump. Another way of accomplishing the cutting up of the solid matter is shown in US 3,096,718. Contrary to recesses, said document shows an impeller seat presenting a cutting 30 blade, which has a sharp edge facing the vanes of the impeller and which in conjunction with said vanes cuts up the solid matter. GB 1,125,376 and US 5,516,261 shows a number of grooves extending in a spiral shape from a centrally located 35 open channel in the impeller seat to the periphery thereof. The function of the grooves is, in conjunction with the vanes of the impeller, to transport the cut up pieces towards the outer wall of the pump housing and further out of the pump WO 2006/135304 PCT/SE2006/000663 3 together with the pumped liquid. In order to ensure a proper function of the grooves, the solid matter has to be cut up into discrete pieces. Otherwise, if long fibers are uncut and connecting different pieces of solid matter, the pieces may 5 be transported in different directions from the center of the impeller seat which may aggravate the clogging of the impeller. . From US 3,128,051 it appears that instead of separate recesses for the cutting up of the solid matter and 10 separate grooves for the transportation of the cut up pieces away from and past the impeller, it is possible to combine the two functions in a single element, which both presents the cutting edge of the recess and the transporting shape of the groove. 15 None of the abovementioned suggestions presents solutions to the drawbacks, or discuss the problems at all, related to the ability to cut long fibers. EP 1,357,294 directed to the applicant, shows a pump which is exposed for solid matter included in unscreened 20 sewage water, but which is not designed to cut up said solid matter. Instead the pump has a groove in the impeller seat for transportation of the entire contaminating subject towards the periphery of the pump housing. Further, the pump has a guide pin, the upper surface of which extends all the 25 way from the surface of the impeller seat to the center of the impeller, and the function of which is to extend the function of the groove towards the center of an open channel in the impeller seat. Thus, there are no indications howsoever on how to ensure reliable cutting up of solid 30 matter having long fibers. Furthermore, submergible pumps are used to pump fluid from basins that are hard to get access to for maintenance and the pumps often operate for long periods of time, not infrequently up to 12 hours a day or more. 35 Therefore it is highly desirable to provide a pump having long durability.

C:\NRPortbflDCCCAB\3%66I0_ I DOC-211//2011 -4 Summary of the Invention In accordance with the invention, there is provided a pump for pumping contaminated liquid including solid matter, comprising a pump housing provided with a rotatable impeller 5 having at least one vane and an impeller seat, the impeller seat presenting at least one recess in the top surface thereof, a sheering/cutting action arising between a cutting edge of said recess and a lower edge of the vane as the impeller rotates relative to the impeller seat, wherein the pump also 10 comprises means for guiding the solid matter towards said recess, the guiding means comprising at least one guide pin and at least one projection, an upper surface of the guide pin extending from a position contiguous to the most inner part of the vane of the impeller towards the impeller seat, and the 15 projection protruding from the top surface of the impeller seat. Thus, the present invention is based on the insight of the importance of guiding the solid matter towards the cutting means of the impeller seat in order to avoid long 20 fibers getting tangled around the vanes of the impeller. In a preferred embodiment of the present invention, the main cutting edge of the recess is located in a position radially distanced from the open channel and generally in parallel with the direction of rotation of the impeller. This 25 means that the shearing/cutting forces, that arise as the WO 2006/135304 PCT/SE2006/000663 5 lower edge of the vane passes the main cutting edge of the vane, is reduced. According to a preferred embodiment, the impeller seat is constituted of a replaceable insert. Then the ability 5 to alter the pump to suit changed conditions, as a consequence of the season and the type of area from which the water emanates, is considerably increased. Different inserts may have different number of grooves, recesses, projections, etc., and/or the shape of the grooves, recesses, projections, 10 etc., may be altered to suit different pollutants having different structure. In addition, also the impeller may be replaced by another impeller having different number of vanes and/or different shape of the vanes. 15 Brief description of the drawings A more complete understanding of the abovementioned and other features and advantages of the present invention will be apparent from the following detailed description of preferred embodiments in conjunction with the appended 20 drawings, wherein: Fig. 1 is a cross sectional view of a pump according to the invention, Fig. 2 is a top view of an impeller and an insert, the 25 impeller being sectioned, Fig. 3 is a bottom view of the impeller and the insert, Fig. 4 is a top view of the insert, and Fig. 5 is a perspective view from below of the impeller. 30 Detailed description of preferred embodiments of the invention Fig 1 shows a pump 1 according to the invention (some parts are removed, such as the engine and an upper case). The invention relates to pumps in general, but in the 35 described embodiment the pump is constituted by a submergible centrifugal pump. The pump 1 comprises a pump housing 2 provided with an impeller 3 and an impeller seat 4. In a preferred WO 2006/135304 PCT/SE2006/000663 6 embodiment of the present invention the impeller seat 4 is constituted by an insert 5 releasably connected to the pump housing 2 by being located in a seat 6 in the pump housing 2 in such a way that the insert cannot rotate relative to the 5 pump housing 2. The impeller 3 is rotatable in the pump housing 2 and is suspended in a drive shaft (not shown) extending from above and inserted in a hole 7, in a centrally located hub 8 of the impeller 3, and secured by means of a screw (not shown) extending from below through the hub 8. 10 Reference is now made to fig 2 as well. The impeller 3 has at least one vane 9 extending from the hub 8 towards the periphery of the impeller 3. Preferably the vane 9 extends in a spiral shape. The direction of rotation of the impeller 3 is clockwise in the embodiment shown in fig 2, and 15 the vanes 9 are extending in the opposite direction, i.e. counter clockwise. In the shown embodiment the impeller 3 has two vanes 9, each extending approximately 360 degrees around the hub 8, but it shall be pointed out that the number of vanes 9 and the length of the vanes 9 may vary greatly, in 20 order to suit different liquids and applications. The insert 5 or the impeller seat 4 has a centrally located open channel 10 and a top surface 11. For the sake of simplicity the term "top surface" as used in the description as well as in the claims means the entire surface of the 25 insert 5 facing the liquid during operation, i.e. both the part contiguous to the open channel 10 and the part facing upwards. The impeller seat 4 preferably presents at least one groove 12 in the top surface 11, the groove 12 extending from the open channel 10 towards the periphery of the impeller 30 seat 4. Preferably the groove 12 extends in a spiral shape in an opposite direction relative to the one of the vanes 9. The number of grooves 12 and their shape and orientation may vary greatly, in order to suit different liquids and applications. The function of the groove 12 is to guide the cut up pieces 35 outwards to the periphery of the pump housing. As the solid matter is being cut up, sludge from the solid matter will fasten underneath the vanes 9 of the impeller 3 and slow down the rotating motion of the impeller 3 and even stop the same.

WO 2006/135304 PCT/SE2006/000663 7 But the groove 12 contribute to keep the vanes 9 clean, by scraping of the sludge each time the vane 9 passes the same. Furthermore, the impeller seat 4 presents at least one recess 13. The function of the recess 13 is, in conjunction with the 5 vanes 9 of the impeller 3, to cut up the solid matter included in the liquid being pumped. The vanes 9 of the impeller 3 sweeps across as the impeller 3 rotates and each time a vane 9 sweep past a recess 13 a decreasing flow area through the recess 13 arises. A cutting edge 15 of the recess 10 13 is made up of two major parts, a first part 16 extending generally in a radial direction in relation to the impeller seat 11 and a second part 17, or main cutting edge, slightly arch shaped and extending generally in parallel with the direction of rotation of the impeller 3. As the vane 9 sweeps 15 across the recess 13, a lower edge 14 of the vane 9 moves or passes in an, angle relative to the cutting edge 15 of the recess 13. More precisely, the solid matter experience a cutting motion as well as a sheering motion. The vane 9 reaches the main cutting edge 17 in a direction from inside 20 and out of the impeller seat 4, which in an energy consumption point of view is a lot better than previously known designs. As may be seen in fig 2 each of the two vanes 9 is in engagement with one recess 13 at a time, and the two vanes 9 are out of phase in relation to each other with 25 regard to their passing of the recesses 13, resulting in a low energy consumption. The shape of the lower edge 14, also known as the tip of the surface, of the vane 9 corresponds, in the axial direction, to the shape of the top surface 11 of the impeller seat 4. The axial distance between the lower 30 edge 14 and the top surface ought to be less than 1 mm in order to get a well defined sheering/cutting action between the lower edge 14 of the vane 9 and the cutting edge 15 of the recess 13. Preferably said distance is less than 0,7 mm and most preferably less than 0,5 mm. At the same time said 35 distance shall be more than 0,1 mm and preferably more than 0,3 mm. If the impeller 3 and the impeller seat 4 are to close to each other a frictional force or a breaking force acts on the vanes 9 of the impeller 3. The edge of the vanes WO 2006/135304 PCT/SE2006/000663 8 9 contiguous to the hub 8 is the leading edge 21 of the vane 9 (see fig 5). Preferably the leading edge 21 of the vane 9 changes to become the lower edge 14 of the vane 9 at a sharp edge. The leading edge 21 is, in the shown embodiment, 5 located directly above the open channel 10 of the impeller seat 4 and the lower edge 14 of the vane 9 is located directly above the top surface 11 of the impeller seat 4. It is a well known problem that solid matter having long fibers tends to get tangled among the vanes 9 of the 10 impeller 3 and winded around the hub 8 of the impeller 3. In order to ensure that the pump 1 does not get clogged it is provided with means for guiding the solid matter towards the recess 13. The guiding means comprises at least one guide pin 18 extending from the top surface 11 of the impeller seat 4, 15 more precisely from the part of the top surface 11 facing the open channel 10. The guide pin 18 extends generally in the radial direction of the impeller seat 4 and is located below the impeller 3 and presents an upper surface 19, which extends from a position contiguous to the most inner part of 20 the vane 9 of the impeller 3 towards the top surface 11 of the impeller seat 4. More precisely, the most inner part of the upper surface 19 of the guide pin 18 is located at approximately the same radial distance from the center of the impeller 3 as the most inner part of the vane 9 of the 25 impeller 3. Preferably the upper surface 19 of the guide pin 18 terminates at a distance from the top surface 11 of the impeller seat 4. If the upper surface 19 of the guide pin 18 should reach all the way out to the top surface 11 of the impeller seat 4 it would guide all the clogging matter 30 towards merely one recess 13 and that would only aggravate the clogging of the pump 1, which might then get totally jammed. The axial distance between the upper surface 19 of the guide pin 18 and the leading edge 21 of the vane 9 ought to be less than 1 mm. 35 In addition, the guide means also comprises at least one projection 20 extending from top surface 11 of the impeller seat 4, more precisely from the part of the top surface 11 facing the open channel 10. The projection 20 is WO 2006/135304 PCT/SE2006/000663 9 located below the impeller 3. The axial distance between the projection 20 and the leading edge 21of the vane 9 ought to be less than 1 mm. Preferably the projection 20 is terminated radially outside of the upper surface 19 of the guide pin 18. 5 As the upper surface 19 of the guide pin 18 terminates radially inside of the projections 20 it will spread the solid matter approximately equally along the top surface 11 facing the open channel 10, and each projection 20 will only guide a part of the solid matter to the corresponding recess 10 13. The projection 20 is located adjacent to and, in the direction of rotation of the impeller 3, after the interacting recess 13. If long fibers tend to get winded around the hub 8, as the impeller 3 rotates, the upper surface 19 of the guide pin 18 forces the fibers outwards 15 towards the projection 20 and the recesses 13. Thereafter, the solid matter gets caught by the projection 20 and the solid matter is forced outwards into the adjacent recess 13 for subsequent cutting up between the lower edge 14 of the vane 9 and the cutting edge 15 of the recess 13. 20 Furthermore, it shall be pointed out that the preferred axial distance between, on one hand, the upper surface 19 of the guide pin 18 and the leading edge 21 of the vane 9, and on the other hand, the projection 20 and the leading edge 21 of the vane 9, shall be the same as described 25 above in connection with the axial distance between the top surface 11 of the impeller seat 4 and the lower edge 14 of the vane 9. Furthermore, the upper surface 19 of the guide pin 18 and the projection 20 corresponds to and are located adjacent to the leading edge 21 of the vane 9 of the impeller 30 3. Finally, It shall be pointed out that the most preferred number of recesses 13, grooves 12 and projections 20 are all five. Furthermore, the pump 1 shall preferably only comprise one guide pin 18. Otherwise the open channel 10 35 should be to obstructed, which would adversely affect the function of the pump 1.

C \NRorbl\CC\CABU%6610_ I.DOC-2/1 1/2011 -10 Feasible modifications of the Invention The invention is not limited only to the embodiments described above and shown in the drawings. Thus, the pump, or more precisely the impeller seat may be modified in all kinds 5 of ways within the scope of the appended claims. It shall be pointed out that the number of vanes preferably shall be different from, preferably larger than, the number of grooves, and, if it is an even number of vanes, the number of grooves shall be odd. Otherwise disturbances may 10 arise. If for instance, the impeller has two vanes the number of grooves should be three or five. Furthermore, said impeller must not hang in the drive shaft as mentioned above. Instead the impeller may float over the impeller seat in another suitable way, e.g. by means of 15 bearings or the like. The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken as, an acknowledgement or admission or any form of suggestion that 20 that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates. Throughout this specification and the claims which follow, unless the context requires otherwise, the word 25 "comprise", and variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims

1. A pump for pumping contaminated liquid including solid matter, comprising a pump housing provided with a rotatable impeller having at least one vane and an impeller seat, the impeller seat presenting at least one recess in the top surface thereof, a sheering/cutting action arising between a cutting edge of said recess and a lower edge of the vane as the impeller rotates relative to the impeller seat, wherein the pump also comprises means for guiding the solid matter towards said recess, the guiding means comprising at least one guide pin and at least one projection, an upper surface of the guide pin extending from a position contiguous to the most inner part of the vane of the impeller towards the impeller seat, and the projection protruding from the top surface of the impeller seat.

2. A pump according to claim 1, wherein the vane extends in a spiral shape from the center of the impeller to the periphery thereof and the lower edge of which has a shape that corresponds to a top surface of the impeller seat.

3. A pump according to claim 1 or 2, wherein the impeller seat presents at least one groove in the top surface thereof, which groove extends from a centrally located open channel in the impeller seat to the periphery thereof.

4. A pump according to claim 3, wherein the groove extends in a spiral shape in the opposite direction relative to the spiral shape of the vane. C \NRPonblIDCC\CAB\396610I DOC-2/11/2011 - 12

5. A pump according to any one of claims 1 to 4, wherein the recess is located adjacent to and open towards the open channel of the impeller seat.

6. A pump according to any one of claims 1 to 5, wherein a main cutting edge of the recess is located in a position radially distanced from the open channel and generally in parallel with the direction of rotation of the impeller, in order to reduce the shearing/cutting forces as the lower edge of the vane will pass said edge.

7. A pump according to any one of the preceding claims, wherein the upper surface of the guide pin is terminated at a distance from the top surface of said impeller seat.

8. A pump according to claim 6, wherein the projection is terminated radially outside the upper surface of the guide pin.

9. A pump according to any one of the preceding claims, wherein the at least one projection is located adjacent to and, in the direction of rotation of the impeller, after said at least one recess.

10. A pump according to any one of the preceding claims, wherein the guide pin and the projection are arranged in the open channel below the impeller.

11. A pump according to any one of the preceding claims, wherein the upper surface of the guide pin and the projection correspond to and are located adjacent to the leading edge of the vane of the impeller. C \NRPnbIl\DCC\CABU966101 DOC-2J1 1/2011 - 13

12. A pump according to any one of claims 2 to 11, wherein the axial distances between, on one hand, the lower edge of the vane of the impeller and the top surface of the impeller seat and, on the other hand, the leading edge of the vane and the upper surface of the guide pin and the projection, are less than 1 mm.

13. A pump according to claim 12, wherein said distances are less than 0,5 mm.

14. A pump according to any one of the preceding claims, wherein the impeller seat is constituted of an insert releasably connected to the pump housing.

15. A pump, substantially as described with reference to the drawings and/or examples.